Lysine-specific demethylase one (“LSD1”), also known as KDM1A, is a flavin-dependent lysine demethylase that removes methyl groups from mono- and dimethylated lysine4 of the histone H3 protein through flavin adenine dinucleotide (FAD) dependent enzymatic oxidation (e.g., see Shi et al., (2004) Cell 119:941-953). In addition, LSD1 demethylates mono- and dimethylation of histone H3 lysine9 in prostate cancer cell lines and is essential for transcriptional regulation mediated by the androgen receptor (Metzger et al., Nature (2005) 437:436-439). LSD1 also demethylates a number of cellular proteins, such as p53, E2F1 and STAT3 and regulates their function.
LSD1 has been reported to be overexpressed in a wide variety of cancers and tissues, including lung cancer, bladder cancer, neuroblastoma, prostate cancer and breast cancer. LSD1 is thought to play a role in cellular proliferation and cancer cell growth by modulating prosurvival gene expression and p53 transcriptional activity (e.g., see Suzuki and Miyata (2011) J. Med. Chem. 54:8236-8250). LSD1 also plays a role in regulating viral gene transcription, e.g., Herpes Simplex Virus (HSV), by demethylating histone H3 lysine9 required for viral gene expression in the host.
With increasing evidence that LSD1 plays a critical role in a diverse set of cancers and diseases, a variety of LSD1 inhibitors, including irreversible LSD1 inhibitors, have been reported and are in clinical development. Irreversible cyclopropyl amine-containing inhibitors, e.g., reviewed in Suzuki and Miyata, ibid, have been shown to be potent inhibitors of the LSD1 enzyme; however, such compounds tend to lack robust cellular potency, have poor metabolic stability and high clearance in vivo.